111
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1 /* Simple data type for real numbers for the GNU compiler.
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2 Copyright (C) 2002-2017 Free Software Foundation, Inc.
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3
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4 This file is part of GCC.
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5
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6 GCC is free software; you can redistribute it and/or modify it under
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7 the terms of the GNU General Public License as published by the Free
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8 Software Foundation; either version 3, or (at your option) any later
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9 version.
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10
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11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
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12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
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13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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14 for more details.
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15
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16 You should have received a copy of the GNU General Public License
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17 along with GCC; see the file COPYING3. If not see
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18 <http://www.gnu.org/licenses/>. */
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19
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20 /* This library supports real numbers;
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21 inf and nan are NOT supported.
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22 It is written to be simple and fast.
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23
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24 Value of sreal is
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25 x = sig * 2 ^ exp
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26 where
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27 sig = significant
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28 (for < 64-bit machines sig = sig_lo + sig_hi * 2 ^ SREAL_PART_BITS)
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29 exp = exponent
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30
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31 One uint64_t is used for the significant.
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32 Only a half of significant bits is used (in normalized sreals) so that we do
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33 not have problems with overflow, for example when c->sig = a->sig * b->sig.
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34 So the precision is 32-bit.
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35
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36 Invariant: The numbers are normalized before and after each call of sreal_*.
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37
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38 Normalized sreals:
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39 All numbers (except zero) meet following conditions:
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40 SREAL_MIN_SIG <= sig && sig <= SREAL_MAX_SIG
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41 -SREAL_MAX_EXP <= exp && exp <= SREAL_MAX_EXP
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42
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43 If the number would be too large, it is set to upper bounds of these
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44 conditions.
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45
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46 If the number is zero or would be too small it meets following conditions:
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47 sig == 0 && exp == -SREAL_MAX_EXP
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48 */
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49
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50 #include "config.h"
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51 #include "system.h"
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52 #include <math.h>
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53 #include "coretypes.h"
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54 #include "sreal.h"
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55 #include "selftest.h"
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56 #include "backend.h"
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57 #include "tree.h"
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58 #include "gimple.h"
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59 #include "cgraph.h"
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60 #include "data-streamer.h"
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61
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62 /* Print the content of struct sreal. */
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63
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64 void
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65 sreal::dump (FILE *file) const
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66 {
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67 fprintf (file, "(%" PRIi64 " * 2^%d)", m_sig, m_exp);
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68 }
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69
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70 DEBUG_FUNCTION void
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71 debug (const sreal &ref)
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72 {
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73 ref.dump (stderr);
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74 }
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75
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76 DEBUG_FUNCTION void
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77 debug (const sreal *ptr)
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78 {
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79 if (ptr)
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80 debug (*ptr);
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81 else
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82 fprintf (stderr, "<nil>\n");
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83 }
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84
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111
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85 /* Shift this right by S bits. Needed: 0 < S <= SREAL_BITS.
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86 When the most significant bit shifted out is 1, add 1 to this (rounding).
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87 */
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88
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89 void
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90 sreal::shift_right (int s)
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91 {
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92 gcc_checking_assert (s > 0);
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93 gcc_checking_assert (s <= SREAL_BITS);
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94 /* Exponent should never be so large because shift_right is used only by
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95 sreal_add and sreal_sub ant thus the number cannot be shifted out from
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96 exponent range. */
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97 gcc_checking_assert (m_exp + s <= SREAL_MAX_EXP);
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98
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99 m_exp += s;
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100
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101 m_sig += (int64_t) 1 << (s - 1);
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102 m_sig >>= s;
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103 }
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104
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105 /* Return integer value of *this. */
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106
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107 int64_t
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108 sreal::to_int () const
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109 {
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110 int64_t sign = SREAL_SIGN (m_sig);
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111
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112 if (m_exp <= -SREAL_BITS)
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113 return 0;
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114 if (m_exp >= SREAL_PART_BITS)
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115 return sign * INTTYPE_MAXIMUM (int64_t);
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116 if (m_exp > 0)
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117 return sign * (SREAL_ABS (m_sig) << m_exp);
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118 if (m_exp < 0)
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119 return m_sig >> -m_exp;
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120 return m_sig;
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121 }
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122
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123 /* Return value of *this as double.
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124 This should be used for debug output only. */
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125
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126 double
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127 sreal::to_double () const
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128 {
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129 double val = m_sig;
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130 if (m_exp)
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131 val = ldexp (val, m_exp);
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132 return val;
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133 }
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134
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135 /* Return *this + other. */
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136
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137 sreal
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138 sreal::operator+ (const sreal &other) const
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139 {
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140 int dexp;
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141 sreal tmp, r;
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142
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143 const sreal *a_p = this, *b_p = &other, *bb;
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144
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145 if (a_p->m_exp < b_p->m_exp)
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146 std::swap (a_p, b_p);
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147
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148 dexp = a_p->m_exp - b_p->m_exp;
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149 r.m_exp = a_p->m_exp;
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150 if (dexp > SREAL_BITS)
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151 {
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152 r.m_sig = a_p->m_sig;
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153 return r;
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154 }
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155
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156 if (dexp == 0)
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157 bb = b_p;
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158 else
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159 {
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160 tmp = *b_p;
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161 tmp.shift_right (dexp);
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162 bb = &tmp;
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163 }
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164
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165 r.m_sig = a_p->m_sig + bb->m_sig;
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166 r.normalize ();
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167 return r;
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168 }
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169
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170
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171 /* Return *this - other. */
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172
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173 sreal
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174 sreal::operator- (const sreal &other) const
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175 {
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176 int dexp;
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177 sreal tmp, r;
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178 const sreal *bb;
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179 const sreal *a_p = this, *b_p = &other;
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180
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181 int64_t sign = 1;
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182 if (a_p->m_exp < b_p->m_exp)
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183 {
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184 sign = -1;
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185 std::swap (a_p, b_p);
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186 }
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187
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188 dexp = a_p->m_exp - b_p->m_exp;
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189 r.m_exp = a_p->m_exp;
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190 if (dexp > SREAL_BITS)
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191 {
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192 r.m_sig = sign * a_p->m_sig;
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193 return r;
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194 }
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195 if (dexp == 0)
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196 bb = b_p;
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197 else
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198 {
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199 tmp = *b_p;
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200 tmp.shift_right (dexp);
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201 bb = &tmp;
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202 }
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203
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204 r.m_sig = sign * (a_p->m_sig - bb->m_sig);
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205 r.normalize ();
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206 return r;
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207 }
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208
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209 /* Return *this * other. */
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210
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211 sreal
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212 sreal::operator* (const sreal &other) const
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213 {
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214 sreal r;
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215 if (absu_hwi (m_sig) < SREAL_MIN_SIG || absu_hwi (other.m_sig) < SREAL_MIN_SIG)
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216 {
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217 r.m_sig = 0;
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218 r.m_exp = -SREAL_MAX_EXP;
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219 }
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220 else
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221 {
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222 r.m_sig = m_sig * other.m_sig;
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223 r.m_exp = m_exp + other.m_exp;
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224 r.normalize ();
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225 }
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226
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227 return r;
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228 }
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229
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230 /* Return *this / other. */
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231
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232 sreal
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233 sreal::operator/ (const sreal &other) const
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234 {
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235 gcc_checking_assert (other.m_sig != 0);
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236 sreal r;
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237 r.m_sig
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238 = SREAL_SIGN (m_sig) * (SREAL_ABS (m_sig) << SREAL_PART_BITS) / other.m_sig;
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239 r.m_exp = m_exp - other.m_exp - SREAL_PART_BITS;
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240 r.normalize ();
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241 return r;
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242 }
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243
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244 /* Stream sreal value to OB. */
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245
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246 void
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247 sreal::stream_out (struct output_block *ob)
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248 {
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249 streamer_write_hwi (ob, m_sig);
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250 streamer_write_hwi (ob, m_exp);
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251 }
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252
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253 /* Read sreal value from IB. */
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254
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255 sreal
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256 sreal::stream_in (struct lto_input_block *ib)
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257 {
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258 sreal val;
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259 val.m_sig = streamer_read_hwi (ib);
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260 val.m_exp = streamer_read_hwi (ib);
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261 return val;
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262 }
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263
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264 #if CHECKING_P
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265
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266 namespace selftest {
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267
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268 /* Selftests for sreals. */
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269
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270 /* Verify basic sreal operations. */
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271
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272 static void
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273 sreal_verify_basics (void)
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274 {
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275 sreal minimum = INT_MIN;
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276 sreal maximum = INT_MAX;
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277
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278 sreal seven = 7;
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279 sreal minus_two = -2;
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280 sreal minus_nine = -9;
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281
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282 ASSERT_EQ (INT_MIN, minimum.to_int ());
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283 ASSERT_EQ (INT_MAX, maximum.to_int ());
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284
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285 ASSERT_FALSE (minus_two < minus_two);
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286 ASSERT_FALSE (seven < seven);
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287 ASSERT_TRUE (seven > minus_two);
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288 ASSERT_TRUE (minus_two < seven);
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289 ASSERT_TRUE (minus_two != seven);
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290 ASSERT_EQ (minus_two, -2);
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291 ASSERT_EQ (seven, 7);
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292 ASSERT_EQ ((seven << 10) >> 10, 7);
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293 ASSERT_EQ (seven + minus_nine, -2);
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294 }
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295
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296 /* Helper function that performs basic arithmetics and comparison
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297 of given arguments A and B. */
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298
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299 static void
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300 verify_aritmetics (int64_t a, int64_t b)
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301 {
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302 ASSERT_EQ (a, -(-(sreal (a))).to_int ());
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303 ASSERT_EQ (a < b, sreal (a) < sreal (b));
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304 ASSERT_EQ (a <= b, sreal (a) <= sreal (b));
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305 ASSERT_EQ (a == b, sreal (a) == sreal (b));
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306 ASSERT_EQ (a != b, sreal (a) != sreal (b));
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307 ASSERT_EQ (a > b, sreal (a) > sreal (b));
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308 ASSERT_EQ (a >= b, sreal (a) >= sreal (b));
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309 ASSERT_EQ (a + b, (sreal (a) + sreal (b)).to_int ());
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310 ASSERT_EQ (a - b, (sreal (a) - sreal (b)).to_int ());
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311 ASSERT_EQ (b + a, (sreal (b) + sreal (a)).to_int ());
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312 ASSERT_EQ (b - a, (sreal (b) - sreal (a)).to_int ());
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313 }
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314
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315 /* Verify arithmetics for interesting numbers. */
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316
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317 static void
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318 sreal_verify_arithmetics (void)
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319 {
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320 int values[] = {-14123413, -7777, -17, -10, -2, 0, 17, 139, 1234123};
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321 unsigned c = sizeof (values) / sizeof (int);
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322
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323 for (unsigned i = 0; i < c; i++)
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324 for (unsigned j = 0; j < c; j++)
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325 {
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326 int a = values[i];
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327 int b = values[j];
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328
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329 verify_aritmetics (a, b);
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330 }
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331 }
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332
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333 /* Helper function that performs various shifting test of a given
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334 argument A. */
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335
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336 static void
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337 verify_shifting (int64_t a)
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338 {
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339 sreal v = a;
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340
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341 for (unsigned i = 0; i < 16; i++)
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342 ASSERT_EQ (a << i, (v << i).to_int());
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343
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344 a = a << 16;
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345 v = v << 16;
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346
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347 for (unsigned i = 0; i < 16; i++)
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348 ASSERT_EQ (a >> i, (v >> i).to_int());
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349 }
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350
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111
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351 /* Verify shifting for interesting numbers. */
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352
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353 static void
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354 sreal_verify_shifting (void)
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355 {
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356 int values[] = {0, 17, 32, 139, 1024, 55555, 1234123};
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357 unsigned c = sizeof (values) / sizeof (int);
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358
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359 for (unsigned i = 0; i < c; i++)
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360 verify_shifting (values[i]);
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361 }
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362
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363 /* Verify division by (of) a negative value. */
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364
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365 static void
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366 sreal_verify_negative_division (void)
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367 {
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368 ASSERT_EQ (sreal (1) / sreal (1), sreal (1));
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369 ASSERT_EQ (sreal (-1) / sreal (-1), sreal (1));
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370 ASSERT_EQ (sreal (-1234567) / sreal (-1234567), sreal (1));
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371 ASSERT_EQ (sreal (-1234567) / sreal (1234567), sreal (-1));
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372 ASSERT_EQ (sreal (1234567) / sreal (-1234567), sreal (-1));
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373 }
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374
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375 /* Run all of the selftests within this file. */
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376
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377 void sreal_c_tests ()
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378 {
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379 sreal_verify_basics ();
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380 sreal_verify_arithmetics ();
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381 sreal_verify_shifting ();
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382 sreal_verify_negative_division ();
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383 }
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384
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385 } // namespace selftest
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386 #endif /* CHECKING_P */
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